Just a few weeks ago Google updated their search to fight back against self-serving reviews.

Now many sites that were gaming the review schemas aren't having their stars show up in the search results.

Only the following 17 categories can have the stars show up:

schema.org/Book
schema.org/Course
schema.org/CreativeWorkSeason
schema.org/CreativeWorkSeries
schema.org/Episode
schema.org/Event
schema.org/Game
schema.org/HowTo
schema.org/LocalBusiness
schema.org/MediaObject
schema.org/Movie
schema.org/MusicPlaylist
schema.org/MusicRecording
schema.org/Organization
schema.org/Product
schema.org/Recipe
schema.org/SoftwareApplication